platform to be tended by divers. Only that 
equipment absolutely needed at the wellhead 
would be located on the ocean floor. 
Saturated diving techniques with diver lockout 
and decompression chambers have been utilized by 
the oil industry to the limit of diver capability. 
During tests in the summer of 1967, divers 
performed functional tasks on a simulated well- 
head in 600 feet of water in the Gulf of Mexico, 
demonstrating man’s ability to do useful work in 
such depths. 
Diver systems will require development of 
power units to augment divers’ underwater phys- 
ical capabilities. Subsea oil field hardware is 
massive; useful work by divers is limited by lack of 
power tools and equipment for direct application 
to subsea hardware. The utility of divers in 
offshore petroleum activities will continue to be 
marginal until underwater work systems are devel- 
loped. 
c Manned Submersibles The need to place sub- 
merged wellheads deeper than routine diving 
depths opens new opportunities for submersible 
vehicles. Several one and two-man submersibles 
have been designed to operate at depths in excess 
of 1,000 feet and could be considered for use in 
future offshore oil fields. Many present submers- 
ible vehicles are unable to develop enough torque 
in their mechanical arms to flange-up wellheads or 
do other heavy work; however, their mechanical 
arms can operate small power tools and valves or 
make adjustments on instruments and controls. 
Submersibles are of limited usefulness in strong 
currents. Future vehicles can be designed to 
overcome most of today’s limitations. 
d. Diverless Remote Control Systems Many 
studies and successful tests already have been 
made on servicing underwater wells with remote 
controlled televiewing robots employing through- 
the-flowline treatment tools, hydraulically con- 
trolled surface lines, and acoustically controlled 
valving systems powered by conventional and 
isotope energy sources. 
A recent report described an ocean-floor well- 
head completion and production maintenance 
system.’? Tests were made with an onshore 
13Rige, A.M., T.W. Childers, C.B. Corley, Jr: “A 
Subsea Completion System for Deep Water,” presented at 
Society of Petroleum Engineers of AIME Symposium, 
May 23-24, 1966. 
VI-174 
nonproducing well in which all normal operations 
were performed. Later, an ocean floor completion 
was made in 60 feet of water about one mile from 
an existing platform, and the tests were repeated. 
Dual flow lines were run to the platform to 
provide for remote production maintenance opera- 
tions in this simulated deep-water satellite well. 
Four hydraulic control lines also were run to the 
platform on the surface for remote operation of 
the underwater christmas tree valves. A submarine 
cable connected the tree with the production 
platform to transmit pressure and valve position 
data. 
Another important feature tested satisfactorily 
was a remote flow line connector for independent 
installation and removal of both the christmas tree 
and the flow lines. The flow lines and the tubing 
strings were two inches in diameter to permit the 
use of pump-down tools; the flow lines provided 
access to the well tubing. The technology of 
remotely controlled tools demands much ingenu- 
ity to insure reliability. Thus, sending a tool to its 
properly intended location, locking it into place, 
testing it to insure proper seating, performing a 
task, and retrieving the tool are an important feat. 
After completion of the test well, all produc- 
tion maintenance and well control operations were 
performed successfully from the remote produc- 
tion platform. The well produced at its full 
allowable rate over an extended period and suc- 
cessfully withstood several hurricanes with no 
damage whatsoever to the underwater christmas 
tree or the flow lines. Experience with the 
pump-down tools indicated good overall reliability 
of this system for remote production maintenance 
operations. This test demonstrated feasibility of 
such a system and will permit large oil fields on 
the ocean floor with only a few strategically 
placed platforms. A number of wells can be drilled 
within a radius of several miles, using the platform 
as home base. 
Suitable power is needed to control ocean floor 
wellheads. An isotope unit to generate power at 
the location may be used or a battery pack 
designed for easy replacement by wireline methods 
from a surface vessel. A power source combining 
an isotope unit with batteries has been perfected 
to operate electric motor driven valves. This 
system has been installed, and has operated for 
several months. This, however, fulfills compara- 
tively low power requirements only. An urgent 
